The efficacy, in terms of electrical efficiency, of an electrical luminary such as a lightbulb is obtained by dividing the total light output (lumens) by the power input (watts), thereby calculating the lumens per watt. As is well known, with conventional incandescent bulbs most of the energy input into a bulb ends up wasted as heat. In most cases the figure approximates 95% or greater. For this reason, a bulb that produces 720 lumens of light requires 60 watts, with a resulting efficacy of 12 lumens per watt. On the other hand, if none of the energy input into a bulb was lost as heat, then only one watt of electricity would produce a light output of 340 lumens!
There have been a number of attempts to solve the problem. For example, fluorescent bulbs have been developed as an alternative light source. However, some people do not care for the appearance of things when viewed in the light given off by these type of bulbs. Furthermore, many of the fluorescent lights which exist are incompatible with standard electrical light sockets. Those which are compatible and which are called compact fluorescent bulbs are often at least twenty times as costly as incandescent bulbs, and as such consumers have not found them to be a viable option. Yet another drawback associated with fluorescent bulbs is that they also contain phosphorus and mercury which raise environmental concerns.
Attempts have also been made to increase the life of incandescent lightbulbs, so that instead of the average life of 750 hours, a lightbulb may last over 1000 hours, with some being advertised as lasting up to 3000 hours. However, associated with lightbulbs which last longer is an increase in price. Still further, the efficacy of such lightbulbs is drastically reduced, since in order to obtain the same amount of light a higher power bulb using more electricity must be utilized.
Therefore it is apparent that the need exists for a simple, yet more efficacious electric lightbulb. It is also apparent that it would be even more desirable if such a lightbulb was also one having a life longer than that associated with such conventional bulbs.